This invention relates to a capped electric lamp provided with:
a translucent lamp vessel which is closed in a gastight manner, which has an axis, and in which an electric element is arranged, said element having a center and being connected to current conductors which issue from the lamp vessel to the exterior; PA1 a lamp cap connected to the lamp vessel and comprising a housing; PA1 which housing is provided with: PA1 contact members connected to the current conductors, PA1 at least one reference means, PA1 at least one locking means for locking the connection of the lamp vessel to the lamp cap, and PA1 at least one coupling means.
Such a capped electric lamp is known from EP-A-0 618 609 to which U.S. Pat. 5,479,066 corresponds. The known lamp is provided with a pressure body to which the lamp vessel is coupled. The pressure body is coupled to the housing by means of a snap connection, the housing having a circumferential wall which runs parallel to the axis. A separate elastic body, for example, a rubber disc or ring, is arranged between the in pressure body and the housing, as seen in axial direction. The elasticity of the disc or ring causes a permanent force to be present between the housing and the pressure body, so that the pressure body with the lamp vessel coupled thereto remains correctly positioned with respect to the housing. A number of functions of the lamp cap, such as contact members, reference and coupling means, are present in positions which are axially shifted relative to one another. As a result, the lamp has a comparatively large constructional dimension in the axial direction.
The known lamp is suitable for being mounted in a reflector. The lamp has a projecting collar which is provided with studs which cooperate with the reflector and by means of which the lamp cap and the reflector can be coupled to one another in a rotary movement. The known lamp is very suitable for use as a vehicle headlamp.
It is a wish of car manufacturers that the actions to be performed in the assembly of car components, such as, for example, lighting units for vehicles, should be as simple as possible. A further wish is that car components should be universally applicable and uniform, i.e. independent of the assembling method, in the case of lamps, for example, plate, front, and back mounting. The known lamp should accordingly be designed for mounting against a support with the bulb forward (back/plate mounting) or with the lamp cap forward (front mounting), as desired. The lamp will then be retained on the support by additional means, while the electric element occupies a previously defined position with respect to this support.
It is a disadvantage of the known capped lamp that it is not universally applicable owing to the comparatively large and highly asymmetrical lamp cap, for example, it is unsuitable for front mounting. A second disadvantage is the difficulty of assembly of the lamp with the lighting unit, on the one hand owing to the comparatively large number of loose components and on the other hand owing to the comparatively complicated rotary movements necessary for coupling the lamp cap to the reflector. A third disadvantage is that tolerances in the dimensions of the housing and the pressure body are accommodated to a limited degree only by the eleastic ring. This involves a considerable risk that the housing and the pressure body bear upon one another without a permanent resilient pressure, so that the housing and the pressure body can move relative to one another and the electric element will be no longer correctly aligned with respect to the support.
DE-B-1 034 268 discloses a capped electric lamp whose glass bulb is closed with a plate of insulating material which lies in a plane which is at least substantially perpendicular to the axis. A hollow cylindrical lamp cap is fixed to the side of the plate facing away from the bulb in a manner not described in any detail. The known bulb, however, is only designed for assemblies with back/plate mounting. It is desirable for various applications, however, to have a lamp available which can be placed against a support with the lamp cap forward.